Abstract [en]

Introduction: Measuring the fascicle length of skeletal muscle is a valuable method that helps us understand the force generating abilities of muscles. It can be studied using 2D ultrasound, which is a cheap and easy method to operate. There are however limitations to this commonly used technique

for measuring long fascicles, such as vastus lateralis as the ultrasound transducers generally used are too short to visualize the entire fascicle, leaving the remaining length to be estimated.

Purpose: To measure the fascicle lengths of vastus lateralis during dynamic and static contractionsusing a modified dual ultrasound transducer technique and to compare the results to previously published methods.

Method: 9 subjects volunteered to participate in the study. Sitting on an isokinetic dynamometer, all performed a maximal isometric contraction at 60° knee angle and a maximal isokinetic contraction at 60°/second while we recoded ultrasound images of the vastus lateralis fascicles. The fascicles were subsequently tracked using 3 different measuring techniques.

Results: We observed a difference between all contractions, although a significant difference was only found comparing the resting length of the isometric contractions. The comparing resting lengths showed a higher difference compared to the length change (from resting to contracting).

Conclusion: The modified technique seems to be a promising method for measuring long fascicle in muscles such as vastus lateralis. Future research is needed to evaluate reliability and validity and a bigger sample size is recommended for more conclusive results.